A study of the frothing capacity of whole milk- 1. A market survey of conventional and organic milks, 2. the effect of clean in place (cip) cleaning solutions

摘要

Gourmet coffee drink consumption is on the rise (NCAUSA 2013). With most of these coffee drinks including milk and/or milk foam, an emphasis on producing quality foam is of high importance. Recent complaints have been received on the failure of milk to foam to expectations of the coffee house (Randolph & Associates 2013). Identifying the source of this failure could enable the milk industry to provide higher foam quality milk to meet the growing needs of coffee houses. A two-part study on the frothing capacity of milk was carried out to investigate potential variations in the market place and to determine the effect of residual cleaning agents used on equipment in the dairy processing industry. For the first part of this study, five different brands of locally available whole bovine milk were compared for their ability to produce quality foam using steam injection from a commercial espresso coffee machine. The effects of common alkaline, acid, and defoaming cleaning products used in high-temperature short-time pasteurization processing plants in CIP (clean-in-place) cleaning method were evaluated in the second phase of this study. Five different brands of whole milk, two of these certified organic, were frothed using steam injection and evaluated based on three variables- steam froth value (SFV), foam volume (FV), and % dissipation. Each sample was frothed five times with three replications, using a different sell by date with each replication. Results for the market survey study indicate there were no differences in SFV, FV, or % dissipation in the brands used when compared to each other. However, when the data collected for organic milks were compared to the data from the conventional milks, there was a significance difference (p<0.05) between SFV, FV, and % dissipation. The organic milks produced lower quality foam as measured by all three variables. In the second part of this study whole milk was used with the addition of a cleaner solution, or water at an addition rate of 1% and 5% for the second phase. There were a total of 12 treatments and a control. The same three variables were analyzed in the cleaning solution study. This study comparing the cleaners to a control (no solution added) show that there were significant differences with the addition of water at 5%, alkaline at 1% and 5%, defoamer at 1% and 5%, alkaline+defoamer at 1% and 5%, and acid+defoamer at 1% and 5% (p<0.05) for SFV. The treatments of water at 1% addition and acid cleaner solution at 1% and at 5% addition rates were not significantly different for SFV. When comparing the rates within the solutions, the water solution and the alkaline+defoamer were significantly different (p0.05) in water at 1%, and both acid addition rates of 1% and 5% when compared to the control. For % dissipation, solutions that differed from the control (p<0.05) were alkaline+defoamer at 1% rate, water at 5%, and acid+defoamer at both 1% and 5% additions. Results from this study demonstrate that cleaning solutions that may end up in milk at abusive levels may be a source of poor frothing characteristics in whole milk.